Recent advances in microsurgery have greatly increased the success rate for replantation surgery following amputation, e.g., traumatic amputation. Whereas two decades previously it was newsworthy when a severed limb was successfully reattached, replantation of fingers, hands, arms, ears, feet, and toes now happens with regular frequency. In particular, severed fingers are commonly replanted with a reattachment success rate of about 87%. Remarkably, in over half of the digit replantation procedures the patient eventually recovers full function of the digit. See Zumiotti et al., “Replantation of digits: factors influencing survival and functional results.” Microsurgery 1994; 15(1):18-21.
Of course, not all traumatic amputations are candidates for replantation. If the limb (or digit) is crushed, or the amputation is in a location where reattachment is not practical (e.g., thigh), replantation is not attempted.
In the event of a “guillotine” injury, however, in which the limb or digit is cleanly separated from the body, replantation is often attempted. In these cases, the most determinative factor of the eventual outcome of replantation is the condition of the body part when it arrives to the operating room. Severed limbs and digits that are clean and kept cold are more likely to result in a good outcome. Despite advances in tissue preservation, the standard of care for preservation of separated tissues (e.g., limbs, digits) has not changed substantially over the last twenty years. Most first responders (e.g., EMS, paramedics) are currently equipped with amputation kits that are merely sterile counterparts to the preservation method of placing the body part in a bag and putting the bag with the body part on ice until reaching the hospital. Once at the hospital, the separated tissues may be preserved in a sterile refrigerator, or other specialized equipment, until the patient is ready for replantation surgery.
While anecdotes of longer separation times are known, replantation is typically not recommended after 12 hours of warm or 24 hours of cold ischemia for digits, and 6 hours of warm or 12 hours of cold ischemia for major replants (e.g. limbs). A portable preservation apparatus which would increase the allowable time between detachment and replantation would likely improve outcomes after traumatic-amputation. Such a system could be used by medical flight crews, EMS teams, and combat paramedics. Such a system would be especially useful in combat zones where an amputee may have to wait hours to be evacuated, or will have a substantial transit time to reach a surgical facility.